Optical emission system including dichroic beam combiner

ABSTRACT

An optical emission spectrometer system includes a light source and a dichroic beam combiner. The light source emits first light in a first direction and second light in a second direction different from the first direction. The dichroic beam combiner receives the first light via a first light path and the second light via a second light path, reflects a portion the first light into an entrance aperture of a light detection and measurement apparatus, and transmits a portion of the second light into the entrance aperture, enabling analysis and measurement of both first and second light characteristics simultaneously. The portion of the first light reflected into the entrance aperture predominately has wavelengths in a first range of wavelengths and the portion of the second light transmitted into the entrance aperture predominately has wavelengths in a second range of wavelengths, different from the first range of wavelengths.

BACKGROUND

Conventional optical emission spectrometers may include inductivelycoupled plasma (ICP) light sources for spectrochemical analysis.Generally, selecting light emitted along an axis of an ICP light source(axial viewing) for detection and measurement provides increasedsignal-to-background ratios, and consequently improved limits ofdetection, as compared to selecting light emitted along a directionperpendicular to the axis of the ICP light source (radial viewing). Thisadvantage is particularly important for certain elements, such asarsenic (As), selenium (Se), lead (Pb) and others having opticalemission lines in the ultraviolet region of the spectrum. However, undercertain circumstances, selecting the light emitted perpendicular to theaxis of the inductively coupled plasma source is advantageous, in thatit enables measurement of a greater range of concentrations and allowsoptimization of the position of light selection to minimizeinter-element interference effects. This may be particularly importantfor easily-ionized elements, such as potassium (K), sodium (Na), lithium(Li) and others having optical emission lines in the visible region ofthe spectrum. In addition, axial viewing generally provides highsensitivity and poor linearity, while radial viewing generally provideslower sensitivity and better linearity.

Attempts have been made to enable selection of light emitted along orperpendicular to the axis of an inductively coupled plasma source. Forexample, light for detection and measurement may be selected as requiredfrom either light emitted along the axis or light at right angles to theaxis of the light source, but not both at the same time. That is, onlyone mode of viewing may be selected at any time. Accordingly, when amodern simultaneous spectrometer is used, for example, it is necessaryto take separate measurements (e.g., separated in time) in each of theaxial and radial viewing modes to obtain best performance for eachelement of interest. In order to achieve simultaneous axial viewing andradial viewing of the light, one spectrometer must be used for axialviewing and another spectrometer must be used for radial viewing. Inother words, conventional systems require either two separate viewsusing one spectrometer (increasing analysis time and sampleconsumption), or two simultaneous views, using separate spectrometersfor each view (a very costly alternative).

SUMMARY

In a representative embodiment, an optical emission spectrometer systemincludes a light source and a dichroic beam combiner. The light sourceis configured to emit first light in a first direction and second lightin a second direction different from the first direction. The dichroicbeam combiner is configured to receive the first light via a first lightpath and the second light via a second light path, to reflect a portionof the first light into an entrance aperture of a light detection andmeasurement apparatus, and to transmit a portion of the second lightinto the entrance aperture, enabling the light detection and measurementapparatus to analyze or measure characteristics of both the first lightand the second light. The portion of the first light reflected into theentrance aperture predominately has wavelengths in a first range ofwavelengths and the portion of the second light transmitted into theentrance aperture predominately has wavelengths in a second range ofwavelengths, different from the first range of wavelengths.

In another representative embodiment, an optical emission spectrometerapparatus includes optical directing means, optical filtering means andoptical combining means. The optical directing means are configured todirect first light emitted from a light source in a first directionalong a first light path to a single light detection and measurementapparatus, and to direct second light emitted from the light source in asecond direction, different from the first direction, along a secondlight path to the same light detection and measurement apparatus. Theoptical filtering means are configured to simultaneously filter thefirst and second light into predominantly different wavelength ranges.The optical combining means are configured to combine the filtered firstand second light prior to the single light detection and measurementapparatus.

In another representative embodiment, an optical emission spectrometersystem includes a plasma light source configured to emit first light ina first direction and second light in a second direction substantiallyperpendicular to the first direction; a first plurality of mirrors fordirecting the first light along a first light path; a second pluralityof mirrors for directing the second light along a second light path; anda mode selector including mode sections corresponding to positions ofthe mode selector. The mode selector is selectively movable, such thatthe first and second light paths intersect one of the mode sections. Themode sections include a dichroic beam combiner, a mirrored section and atransparent section. The dichroic beam combiner is configured to reflectwavelengths of the first light predominantly in a predetermined firstwavelength range into an entrance aperture of a detector, and totransmit wavelengths of the second light predominantly in apredetermined second wavelength range into the entrance aperture,enabling analysis of both the first light and the second light, thesecond wavelength range being different from the first wavelength range.The mirrored section is configured to reflect all wavelengths of thefirst light into the entrance aperture of the detector, and to reflectall wavelengths of the second light away from the entrance aperture ofthe detector, enabling analysis of the first light. The transparentsection is configured to transmit all wavelengths of the second lightinto the entrance aperture of the detector, and to transmit allwavelengths of the first light away from the entrance aperture of thedetector, enabling analysis of the second light.

BRIEF DESCRIPTION OF THE DRAWINGS

The illustrative embodiments are best understood from the followingdetailed description when read with the accompanying drawing figures. Itis emphasized that the various features are not necessarily drawn toscale. In fact, the dimensions may be arbitrarily increased or decreasedfor clarity of discussion. Wherever applicable and practical, likereference numerals refer to like elements.

FIG. 1 is an isometric view of an optical emission spectrometer system,according to a representative embodiment.

FIG. 2 is a cross-sectional view of a dichroic beam combiner of theoptical emission spectrometer system of FIG. 1, according to arepresentative embodiment.

FIG. 3 is an isometric view of an optical emission spectrometer system,according to a representative embodiment.

FIG. 4 is a top plan view of a movable member, including a dichroic beamcombiner, of the optical emission spectrometer system of FIG. 3,according to a representative embodiment.

FIG. 5 is a cross-sectional view of the movable member of FIGS. 3 and 4in a first position, according to a representative embodiment.

FIG. 6 is a cross-sectional view of the movable member of FIGS. 3 and 4in a second position, according to a representative embodiment.

FIG. 7 is a cross-sectional view of the movable member of FIGS. 3 and 4in a third position, according to a representative embodiment.

FIG. 8 illustrates a trace indicating a portion of light transmitted bya dichroic beam combiner, depending on wavelength, according to arepresentative embodiment.

FIG. 9 illustrates a trace indicating a portion of light reflected by adichroic beam combiner, depending on wavelength, according to arepresentative embodiment.

DETAILED DESCRIPTION

In the following detailed description, for purposes of explanation andnot limitation, illustrative embodiments disclosing specific details areset forth in order to provide a thorough understanding of embodimentsaccording to the present teachings. However, it will be apparent to onehaving had the benefit of the present disclosure that other embodimentsaccording to the present teachings that depart from the specific detailsdisclosed herein remain within the scope of the appended claims.Moreover, descriptions of well-known devices and methods may be omittedso as not to obscure the description of the example embodiments. Suchmethods and devices are within the scope of the present teachings.

An optical emission spectrometer system may be used for spectrochemicalanalysis. According to various embodiments, the optical emissionspectrometer system includes an inductively coupled plasma light source,an optical filter, and a spectrometer, or other light detection andmeasurement apparatus. In an embodiment, light is emitted by the plasmalight source in a direction along a longitudinal axis of the plasmalight source (axially-emitted light) and in a direction different fromthe direction along the longitudinal axis of the plasma light source(radially-emitted). For example, the radially-emitted light may beemitted in a direction substantially perpendicular to the longitudinalaxis. The optical filter directs portions of both the axially-emittedlight and the radially emitted light to the spectrometer based onwavelengths, where each portion includes wavelengths predominatelywithin a range above or below a predetermined wavelength value. Thespectrometer is thus able to simultaneously collect the axially-emittedlight (axial viewing) and the radially-emitted light (radial viewing).For example, the optical filter may allow only light predominatelyhaving wavelengths shorter than the predetermined wavelength value toenter the spectrometer for axial viewing, and may allow only lightpredominately having wavelengths above the predetermined wavelengthvalue to enter the spectrometer for radial viewing.

Generally, advantages of axial viewing are typically associated withelements having their most sensitive emission lines in the ultravioletregion of the spectrum, whereas advantages of radial viewing aretypically associated with elements having their most sensitive emissionlines in the visible region of the spectrum. The optical emissionspectrometer system, according to representative embodiments, enablessimultaneous axial viewing and radial viewing, as mentioned above. Thus,the single spectrometer is able to receive and measure light intensityfrom two light paths simultaneously.

FIG. 1 is an isometric view of an optical emission spectrometer system,according to a representative embodiment.

Referring to FIG. 1, optical emission spectrometer system 100 includes alight source 101 for emitting light that can be detected and measuredwith respect to wavelength by a light detection and measurementapparatus 140, e.g., for detecting and measuring light and analyzingwavelength. The light source 101 may be an inductively coupled plasmalight source, for example. Also, the light detection and measurementapparatus 140 may be a monochromator or a polychromator, for example,together with at least one associated light detector. The light from thelight source 101 enters the light detection and measurement apparatus140 via slit or entrance aperture 145.

The optical emission spectrometer system 100 further includes firstlight path 110 and second light path 120. The first light path 110includes a first set of mirrors, depicted by representative mirrors 111and 112, configured to direct light emitted by the light source 101 in afirst direction (referred to as first light 115) onto an optical filter,such as representative dichroic beam combiner 130. In the depictedexample, the first light 115 is emitted axially from the light source101, i.e., along the longitudinal axis, and is reflected by the mirror111 onto the mirror 112, and by the mirror 112 onto the dichroic beamcombiner 130. The second light path 120 includes a second set ofmirrors, depicted by representative mirrors 121 and 122, configured todirect light emitted by the plasma light source 101 in a seconddirection (referred to as second light 125), substantially perpendicularto the first direction, onto the dichroic beam combiner 130. In thedepicted embodiment, the second light 125 is emitted radially from thelight source 101, and is reflected by the mirror 121 onto the mirror122, and by the mirror 122 onto the dichroic beam combiner 130.

Of course, the first direction of the first light 115 emitted from thelight source 101 and the second direction of the second light 125emitted from the light source 101 may vary without departing from thescope of the present teachings. For example, the first direction of thefirst light 115 may be at an angle departing from the longitudinal axisof the light source 101, rather than along the longitudinal axis.Likewise, the second direction of the second light 125 may be anydirection different from the first direction, and therefore does notneed to be substantially perpendicular to the longitudinal axis of thelight source 101 and/or substantially perpendicular to the firstdirection of the first light 115.

In various embodiments, at least one of the mirrors 111, 112 in thefirst light path 110 and at least one of the mirrors 121, 122 in thesecond light path 120 may be adjustable using an electric motor, such asa step motor, for example. Adjustment of the mirrors 111, 112 and 121,122 enables the first and second light 115 and 125 to be properlyfocused onto the dichroic beam combiner 130 and/or the entrance aperture145, respectively. The motor may be manually or automatically operable,e.g., using a controller or other processing device (not shown). Forexample, the processing device may be implemented by a computerprocessor, application specific integrated circuits (ASICs),field-programmable gate arrays (FPGAs), or combinations thereof, usingsoftware, firmware, hard-wired logic circuits, or combinations thereof.When using a processor, a memory may be included, such as anon-transitory computer readable medium, for storing executablesoftware/firmware and/or executable code that allows it to perform thevarious functions.

The dichroic beam combiner 130 receives the first light 115 via thefirst light path 110 and the second light 125 via the second light path120. In the depicted embodiment, the dichroic beam combiner 130 isconfigured to reflect only a portion the first light 115 into theentrance aperture 145 of the light detection and measurement apparatus140, and to transmit a only portion of the second light 125 into theentrance aperture 145, enabling the light detection and measurementapparatus 140 to analyze and measure simultaneously characteristics ofboth the first light 115 and the second light 125 using the respectiveportions of the first light 115 and the second light 125. Of course, inalternative embodiments, the dichroic beam combiner 130 may beconfigured to transmit the portion the first light 115 and to reflectthe portion of the second light 125 into the entrance aperture 145 ofthe light detection and measurement apparatus 140, without departingfrom the scope of the present teachings.

More particularly, the dichroic beam combiner 130 reflects or transmitsthe portions of the first and second light 115 and 125 depending onwavelength. For example, the dichroic beam combiner 130 has anassociated predetermined wavelength value, which is essentially ademarcation between wavelengths that are predominately reflected andwavelengths that are predominately transmitted by the dichroic beamcombiner 130. For example, the dichroic beam combiner 130 may reflectportions of the first and second light 115 and 125 predominantly havingwavelengths below the predetermined wavelength value, and transmitportions of the first and second light 115 and 125 predominantly havingwavelengths above the predetermined wavelength value. In this context,predominantly means greater than 50 percent of the total amount of therespective portion of light. In other words, in this example, more than50 percent of the portion of the first light 115 reflected by thedichroic beam combiner 130 has wavelengths below the predeterminedwavelength value. The dichroic beam combiner 130 thus effectivelyfilters the first and second light 115 and 125 into predominantlydifferent wavelength ranges, and combines the filtered first and secondlight 115 and 125 for input into the entrance aperture 145 of the lightdetection and measurement apparatus 140.

The predetermined wavelength value may be about 500 nanometers (nm), forexample, although other predetermined wavelength values may beimplemented, to provide unique benefits for any particular situation orto meet application specific design requirements, without departing fromthe scope of the present teachings. The wavelengths below thepredetermined wavelength value (e.g., less than 500 nm) may be referredto as a first range of wavelengths, and the wavelengths above thepredetermined wavelength value (e.g., greater than 500 nm) may bereferred to as a second range of wavelengths, for convenience ofexplanation. Notably, the optical filter may be implemented usingfiltering means augmenting the dichroic beam combiner 130, as well. Afurther variation of this embodiment includes optical filters placedseparately in the first light path 110 and second light path 120, inorder to select substantially different wavelength ranges from the firstlight 115 and the second light 125, and a beam combiner to recombine thefiltered first and second light 115 and 125.

FIG. 2 is a cross-sectional view of the dichroic beam combiner 130 ofthe optical emission spectrometer system 100 shown in FIG. 1, accordingto a representative embodiment. Referring to FIG. 2, the dichroic beamcombiner 130 is tilted so that the portions of the first and secondlight 115 and 125 that it reflects are either directed into or away fromthe entrance aperture 145 of the light detection and measurementapparatus 140. More particularly, when the dichroic beam combiner 130receives the first light 115, it reflects a reflected portion 115R intothe entrance aperture 145 and transmits a transmitted portion 115T awayfrom the entrance aperture 145 (meaning the transmitted portion 115Tdoes not enter the entrance aperture 145). When the dichroic beamcombiner 130 receives the second light 125, at the same time asreceiving the first light 115, it reflects a reflected portion 125R awayfrom the entrance aperture 145 and transmits a transmitted portion 125Tinto the entrance aperture 145.

As mentioned above, since the dichroic beam combiner 130 reflectsportions of the first and second light 115 and 125 predominately havingwavelengths below the predetermined wavelength value, the reflectedportion 115R of the first light 115 and the reflected portion 125R ofthe second light 125 have wavelengths predominately in the first rangeof wavelengths. Therefore, in the depicted example, the light detectionand measurement apparatus 140 receives the portion of the first light115 having wavelengths predominately in the first range of wavelengths.Likewise, since the dichroic beam combiner 130 transmits portions of thefirst and second light 115 and 125 predominately having wavelengthsabove the predetermined wavelength value, the transmitted portion 115Tof the first light 115 and the transmitted portion 125T of the secondlight 125 have wavelengths predominately in the second range ofwavelengths. Therefore, in the depicted example, the light detection andmeasurement apparatus 140 receives the portion of the second light 125having wavelengths predominately in the second range of wavelengths.

In other words, the light detection and measurement apparatus 140generally receives shorter wavelengths (e.g., in the ultraviolet regionof the spectrum) of the first light 115 and longer wavelengths (e.g., inthe visible region of the spectrum) of the second light 125. Of course,in alternative embodiments, the dichroic beam combiner 130 may beconfigured to transmit portions of the first and second light 115 and125 predominately having wavelengths below the predetermined wavelengthvalue, and to reflect portions of the first and second light 115 and 125predominately having wavelengths above the predetermined wavelengthvalue, without departing from the scope of the present teachings.

FIG. 8 shows trace 800 indicating portions of light (such as the firstand second light 115 and 125) transmitted by the dichroic beam combiner130 (transmission model), and FIG. 9 shows trace 900 indicating portionsof light reflected by the dichroic beam combiner 130 (reflection model),depending on wavelength. In the depicted examples, the predeterminedwavelength value at which transmitted and reflected light is separatedis assumed to be about 500 nm.

Referring to FIG. 8, the portion of light transmitted by the dichroicbeam combiner 130 predominantly has wavelengths above about 500 nm, asdiscussed above. That is, the dichroic beam combiner 130 generallytransmits light having wavelengths longer than about 500 nm and does nottransmit (or reflects) light having wavelengths shorter than about 500nm. In the depicted example, the dichroic beam combiner 130 transmitsbetween about 75% to about 90% of the light having wavelengths longerthan about 500 nm, but transmits only about 0% to about 10% of the lighthaving wavelengths shorter than about 500 nm.

Referring to FIG. 9, the portion of light reflected by the dichroic beamcombiner 130 predominantly has wavelengths below about 500 nm, asdiscussed above. That is, the dichroic beam combiner 130 generallyreflects light having wavelengths shorter than about 500 nm and does notreflect (or transmits) light having wavelengths longer than about 500nm. In the depicted example, the dichroic beam combiner 130 reflectsbetween about 70% to about 95% of the light having wavelengths shorterthan about 500 nm (and above about 200 nm), but reflects only about 10%to about 15% of the light having wavelengths longer than about 500 nm.

In addition to reflecting a portion of light and transmitting a portionof light based on wavelength, described above, a user of an opticalemission spectrometer system may want to reflect or transmit light ofall wavelengths under various circumstances. To do so would generallyrequire replacement of the dichroic beam combiner with a reflectingsurface or a transmitting surface, respectively, which would be timeconsuming and otherwise inefficient.

FIG. 3 is an isometric view of an optical emission spectrometer system,according to a representative embodiment, which includes a movablemember having different sections to control the directivity of light,e.g., emitted by an inductively coupled plasma light source. FIG. 4 is atop plan view of the movable member included in the optical emissionspectrometer system of FIG. 3, according to a representative embodiment.

Referring to FIGS. 3 and 4, optical emission spectrometer system 200 issubstantially the same as the optical emission spectrometer system 100of FIG. 1, with the addition of movable member 230. That is, the opticalemission spectrometer system 200 includes light source 101 for emittinglight that can be detected and measured with respect to wavelength bylight detection and measurement apparatus 140. The optical emissionspectrometer system 200 further includes first light path 110 and secondlight path 120. The first light path 110 includes representative mirrors111 and 112, configured to direct light emitted by the light source 101in the first direction (first light 115) onto the movable member 230,and the second light path 120 includes representative mirrors 121 and122, configured to direct light emitted by the light source 101 in thesecond direction (second light 125), substantially perpendicular to thefirst direction, onto the movable member 230.

In the depicted embodiment, the movable member 230 includes three modesections respectively corresponding to first, second and third positionsof the movable member 230. The three mode sections include dichroic beamcombiner 231 (or other optical filter), mirrored section 232 andtransparent section 233. The movable member 230 is selectively movable,such that operation of the movable member 230 places one of the dichroicbeam combiner 231, the mirrored section 232 and the transparent section233 into the first and second light paths 110 and 120 for receiving thefirst and second light 115 and 125, respectively.

In the depicted embodiment, the movable member 230 is a mode wheelrotatable around axis 236, using a hub and shaft arrangement 237, forexample. The mode wheel is substantially circular in shape, and thedichroic beam combiner 231, the mirrored section 232 and the transparentsection 233 respectively occupy equal sized sectors (pie-shaped regions)of the mode wheel. The movable member 230 is thus rotatable among afirst position for selecting the dichroic beam combiner 231, a secondposition for selecting the mirrored section 232 and a third position forselecting the transparent section 233.

Rotation of the movable member 230 may be enabled by controllablerotating means (not shown), such as a manual selector and/or an electric(step) motor, for example. The motor may be manually or automaticallyoperable, e.g., using the controller or other processing device (notshown), discussed above. For example, the processing device may beimplemented by a computer processor, ASICs, FPGAs, or combinationsthereof, using software, firmware, hard-wired logic circuits, orcombinations thereof. When using a processor, a memory may be included,such as a non-transitory computer readable medium, for storingexecutable software/firmware and/or executable code that allows it toperform the various functions.

Of course, the movable member 230 may have different configurationswithout departing from the scope of the present teachings. For example,the movable member 230 may include a rotatable mode wheel having any ofa variety of shapes other than a circle and/or sectors (or sections)having corresponding sizes/shapes different from one another. Inaddition, the movable member 230 may not be rotatable, but rather mayincorporate other means of movement to enable selection of the dichroicbeam combiner 231, the mirrored section 232 or the transparent section233. For example, the movable member 230 may be slideable in variousdirections among the first, second and third positions in order to placethe corresponding one of the dichroic beam combiner 231, the mirroredsection 232 and the transparent section 233 into the first and secondlight paths 110 and 120.

FIG. 5 is a cross-sectional view of the movable member 230 of theoptical emission spectrometer system 200 shown in FIGS. 3 and 4 in afirst position, according to a representative embodiment. Referring toFIG. 5, the first position places the dichroic beam combiner 231 withinthe first and second light paths 110 and 120. The movable member 230 istilted so that the portions of the first and second light 115 and 125reflected by the dichroic beam combiner 231 are either directed into oraway from the entrance aperture 145 of the light detection andmeasurement apparatus 140, as discussed above. When the dichroic beamcombiner 231 receives the first light 115, it reflects a reflectedportion 115R into the entrance aperture 145 and transmits a transmittedportion 115T away from the entrance aperture 145 (meaning thetransmitted portion 115T does not enter the entrance aperture 145). Whenthe dichroic beam combiner 231 receives the second light 125, at thesame time as receiving the first light 115, it reflects a reflectedportion 125R away from the entrance aperture 145 and transmits atransmitted portion 125T into the entrance aperture 145. Each of thereflected portions 115R and 125R and the transmitted portions 115T and125T is determined by the wavelengths of the first light 115 and thesecond light 125, respectively, in comparison to a predeterminedwavelength value, as discussed above.

FIG. 6 is a cross-sectional view of the movable member 230 of theoptical emission spectrometer system 200 shown in FIGS. 3 and 4 in asecond position, according to a representative embodiment. Referring toFIG. 6, the second position places the mirrored section 232 within thefirst and second light paths 110 and 120. The movable member 230 istilted so that the portions of the first light 115 reflected by themirrored section 232 are directed into the entrance aperture 145 of thelight detection and measurement apparatus 140. That is, when themirrored section 232 receives the first light 115, it reflects areflected portion 115R into the entrance aperture 145, where thereflected portion 115R includes substantially all wavelengths of thefirst light 115. When the mirrored section 232 receives the second light125, at the same time as receiving the first light 115, it reflects areflected portion 125R away from the entrance aperture 145, where thereflected portion 125R includes substantially all of the wavelengths ofthe second light 125. In other words, when the movable member 230 is inthe second position, the light detection and measurement apparatus 140only receives the first light 115 via the entrance aperture 145,including substantially all of the wavelengths.

FIG. 7 is a cross-sectional view of the movable member 230 of theoptical emission spectrometer system 200 shown in FIGS. 3 and 4 in athird position, according to a representative embodiment. Referring toFIG. 6, the third position places the transparent section 233 within thefirst and second light paths 110 and 120. When the transparent section233 receives the first light 115, it transmits a transmitted portion115T away from the entrance aperture 145, where the transmitted portion115T includes substantially all of the wavelengths of the first light115. When the transparent section 233 receives the second light 125, atthe same time as receiving the first light 115, it transmits atransmitted portion 125T into the entrance aperture 145, where thetransmitted portion 125T includes substantially all of the wavelengthsof the second light 125. In other words, when the movable member 230 isin the third position, the light detection and measurement apparatus 140only receives the second light 125 via the entrance aperture 145,including substantially all of the wavelengths.

Generally, the mirrored section 232 in the movable member 230 enablesmeasurement of substantially the entire wavelength range of the axiallyemitted light (first light 115), in the depicted illustrativeconfiguration, which allows for more sensitive detection of light in thewavelengths that would otherwise have been transmitted away from theaperture 145 by the dichroic beam combiner (e.g., beam combiner 231).Better detection limits may be achieved because the axial light path(first light path 110) is approximately ten to forty times more intensethan the radial light path (second light path 120), but axial onlymeasurements may suffer from Easily Ionized Element Interferences wheneasily ionized elements are present. The transparent section 233 in themovable member 230 enables measurement of substantially the entirewavelength range of the radially emitted light (second light 125), inthe depicted illustrative configuration. The availability of the lessintense radial light increases the dynamic range of measurement (whenused in conjunction with the axial light measurements) by allowingmeasurement of intense sample concentrations that would otherwiseover-range an axial light measurement. This may result in lowerdetection limits due to the reduction of available light compared to theaxial light path.

According to various embodiments, measurements of the intensity ofaxially-emitted light (e.g., originating along the direction of the axisof the light source) and measurements of the intensity ofradially-emitted light (e.g., originating along the directionsubstantially perpendicular to the axis of the light source) are madesimultaneously by the same spectrometer. In contrast, conventionalsystems measure axially-emitted light and radially-emitted lightsequentially using one spectrometer, or simultaneously using twospectrometers. Therefore, in carrying out an analysis of a sample forwhich it is required to make measurements of both axially-emitted lightand radially-emitted light using a single spectrometer capable ofsimultaneous measurements, according to various embodiments, only oneset of measurements needs to be made. Therefore, the measurements may becompleted in about half the time, as compared to conventional systems.

While specific embodiments are disclosed herein, many variations arepossible, which remain within the concept and scope of the invention.Such variations would become clear after inspection of thespecification, drawings and claims herein. The invention therefore isnot to be restricted except within the scope of the appended claims.

What is claimed is:
 1. An optical emission spectrometer system,comprising: a light source configured to emit first light in a firstdirection and second light in a second direction different from thefirst direction; and a dichroic beam combiner configured to receive thefirst light via a first light path and the second light via a secondlight path, to reflect a portion of the first light into an entranceaperture of a light detection and measurement apparatus, and to transmita portion of the second light into the entrance aperture, wherein theportion of the first light reflected into the entrance aperturepredominately has wavelengths in a first range of wavelengths and theportion of the second light transmitted into the entrance aperturepredominately has wavelengths in a second range of wavelengths differentfrom the first range of wavelengths.
 2. The system of claim 1, whereinthe first direction is along an axis of the light source and the seconddirection is substantially perpendicular to the axis of the lightsource.
 3. The system of claim 1, wherein the first range of wavelengthsis below a predetermined wavelength value, and the second range ofwavelengths is above the predetermined wavelength value.
 4. The systemof claim 3, wherein the predetermined wavelength value is about 500 nm.5. The system of claim 1, wherein the first range of wavelengths isabove a predetermined wavelength value, and the second range ofwavelengths is below the predetermined wavelength value.
 6. The systemof claim 5, wherein the predetermined wavelength value is about 500 nm.7. The system of claim 1, further comprising: a movable member includingthe dichroic beam combiner, a mirrored section and a transparentsection, the movable member being operable to place one of the dichroicbeam combiner, the mirrored section and the transparent section into thefirst and second light paths for receiving the first and second light.8. The system of claim 7, wherein the mirrored section of the movablemember is configured to reflect substantially all wavelengths of thefirst light into the entrance aperture of the detector, and to reflectsubstantially all wavelengths of the second light away from the entranceaperture of the detector.
 9. The system of claim 7, wherein thetransparent section of the movable member is configured to transmitsubstantially all wavelengths of the first light away from the entranceaperture of the detector, and to transmit substantially all wavelengthsof the second light into the entrance aperture of the detector.
 10. Thesystem of claim 1, wherein the first light path comprises a first set ofmirrors configured to direct the first light to the dichroic beamcombiner; and wherein the second light path comprises a second set ofmirrors configured to direct the second light to the dichroic beamcombiner.
 11. The system of claim 1, wherein the light detection andmeasurement apparatus comprises one of a monochromator or apolychromator, and at least one associated light detector.
 12. Thesystem of claim 1, wherein the light source comprises an inductivelycoupled plasma light source.
 13. An optical emission spectrometerapparatus, comprising: optical directing means configured to directfirst light emitted from a light source in a first direction along afirst light path to a single light detection and measurement apparatus,and to direct second light emitted from the light source in a seconddirection, different from the first direction, along a second light pathto the same light detection and measurement apparatus; optical filteringmeans configured to simultaneously filter the first and second lightinto predominantly different wavelength ranges; and optical combiningmeans to combine the filtered first and second light prior to the singlelight detection and measurement apparatus.
 14. The system of claim 13,wherein the light detection and measurement apparatus comprises one of amonochromator or a polychromator, and at least one associated lightdetector.
 15. The apparatus according to claim 13 wherein at least oneof the optical filtering means and the optical combining means comprisesa dichroic beam combiner configured to reflect a portion of the firstlight having wavelengths below a predetermined value and to transmit aportion of the second light having wavelengths above the nominal valueinto the entrance aperture.
 16. The apparatus according to claim 13wherein at least one of the optical filtering means and the opticalcombining means comprises a dichroic beam combiner configured totransmit a portion of the first light having wavelengths below a nominalvalue and to reflect a portion of the second light having wavelengthsabove the nominal value into the entrance aperture.
 17. The apparatus ofclaim 13, further comprising: a movable member selectively movable amongfirst, second and third positions corresponding to the optical filteringmeans, a mirrored section and a transparent section, respectively,wherein operation of the movable member places one of the opticalfiltering means, the mirror section and the transparent section into thefirst and second light paths for receiving the first and second light.18. The apparatus of claim 17, wherein the mirror section is configuredto reflect substantially all wavelengths of only one of the first andsecond light into the entrance aperture when the movable member is inthe second position, and wherein the transparent section is configuredto transmit substantially all wavelengths of only one of the first andsecond light into the entrance aperture when the movable member is inthe third position.
 19. An optical emission spectrometer system,comprising: a plasma light source configured to emit first light in afirst direction and second light in a second direction substantiallyperpendicular to the first direction; a first plurality of mirrors fordirecting the first light along a first light path; a second pluralityof mirrors for directing the second light along a second light path; anda mode selector comprising a plurality of mode sections corresponding toa plurality of positions of the mode selector, the mode selector beingselectively movable such that the first and second light paths intersectone of the plurality of mode sections, the plurality of mode sectionscomprising: a dichroic beam combiner configured to reflect wavelengthsof the first light predominantly in a predetermined first wavelengthrange into an entrance aperture of a detector, and to transmitwavelengths of the second light predominantly in a predetermined secondwavelength range into the entrance aperture, enabling analysis of boththe first light and the second light, the second wavelength range beingdifferent from the first wavelength range; a mirrored section configuredto reflect all wavelengths of the first light into the entrance apertureof the detector, and to reflect all wavelengths of the second light awayfrom the entrance aperture of the detector, enabling analysis of thefirst light; and a transparent section configured to transmit allwavelengths of the second light into the entrance aperture of thedetector, and to transmit all wavelengths of the first light away fromthe entrance aperture of the detector, enabling analysis of the secondlight.
 20. The system of claim 19, wherein the first wavelength rangecomprises wavelengths below a predetermined wavelength value and thesecond wavelength range comprises wavelengths above the predeterminedwavelength value.